Local and federal officials gathered Thursday, Oct. 4, 2018, at the Allentown City Hall council chamber for a news conference on the Allentown car explosion. Officials said Jacob Schmoyer, 26, intentionally set off the blast that killed himself his son, 2, and David Hallman, 66. (Rick Kintzel / The Morning Call)

Local and federal officials gathered Thursday, Oct. 4, 2018, at the Allentown City Hall council chamber for a news conference on the Allentown car explosion. Officials said Jacob Schmoyer, 26, intentionally set off the blast that killed himself his son, 2, and David Hallman, 66. (Rick Kintzel / The Morning Call)

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Local and federal officials gathered Thursday, Oct. 4, 2018, at the Allentown City Hall council chamber for a news conference on the Allentown car explosion. Officials said Jacob Schmoyer, 26, intentionally set off the blast that killed himself his son, 2, and David Hallman, 66. (Rick Kintzel / The Morning Call)

Local and federal officials gathered Thursday, Oct. 4, 2018, at the Allentown City Hall council chamber for a news conference on the Allentown car explosion. Officials said Jacob Schmoyer, 26, intentionally set off the blast that killed himself his son, 2, and David Hallman, 66. (Rick Kintzel / The Morning Call)

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Full video: The Allentown car explosion was an 'intentional act,' by Jacob Schmoyer, 26, who intended to kill his 2-year-old son Jonathan and 66-year-old David Hallman, officials said at a news conference Thursday, Oct. 4, 2018. (Kayla Dwyer / The Morning Call)

Full video: The Allentown car explosion was an 'intentional act,' by Jacob Schmoyer, 26, who intended to kill his 2-year-old son Jonathan and 66-year-old David Hallman, officials said at a news conference Thursday, Oct. 4, 2018. (Kayla Dwyer / The Morning Call)

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The Allentown car explosion was an 'intentional act,' by Jacob Schmoyer, 26, who intended to kill his 2-year-old son Jonathan and 66-year-old David Hallman, officials said at a news conference Thursday, Oct. 4, 2018. (Monica Cabrera / The Morning Call)

The Allentown car explosion was an 'intentional act,' by Jacob Schmoyer, 26, who intended to kill his 2-year-old son Jonathan and 66-year-old David Hallman, officials said at a news conference Thursday, Oct. 4, 2018. (Monica Cabrera / The Morning Call)

He wanted out of the world, but he didn’t intend to go alone. So he built a bomb, put his toddler son in the back seat of his car, lured an acquaintance into the front seat and set off the explosion that shattered an Allentown city block and sent families and friends reeling in shock.

That, broadly, is the story sketched out Thursday by federal agents who spent nearly six days piecing together — literally and figuratively — the events that led to Saturday night’s car blast on Turner Street in Center City.

The means was a homemade bomb made of two legally obtainable chemicals. The motive, so far as it can be known, was laid out in letters mailed by Schmoyer on the day of the explosion, which reached their recipients — family members and the Allentown Police Department — on Tuesday and Wednesday.

“The crux of the letters, he was very unhappy with his life, described himself in some negative terms, admitted to a number of other criminal acts, from petty thefts to burglaries,” said Special Agent Don Robinson of the Bureau of Alcohol, Tobacco, Firearms and Explosives. “He indicated a desire not to stick around and unfortunately … his intent to take Mr. Hallman and his son with him.

“He was miserable. … There was a lot of hatred there, some directed at Mr. Hallman and some at his son,” Robinson said.

Because of the letters, interviews with family, friends and witnesses, and a massive forensic reconstruction of the incident, Robinson said, “It is the collective assessment and opinion of the entire investigative team that this was an intentional act … by Jacob Schmoyer.”

The explosion scattered body parts and car parts over most of a city block. It displaced residents of Turner Street between Seventh and Eighth streets and damaged several buildings to the point where they are uninhabitable.

Rick Kintzel / The Morning Call

An image taken from a monitor during Thursday's news conference shows Jacob Schmoyer's reconstructed car post-explosion.

Assistant U.S. Attorney John Gallagher called the crime scene a “nightmare” where emergency staff worked around the clock for five days.

“We asked our police officers to make sense of what was really a war zone,” he said.

No one was walking past the car when it exploded, though the Center City street is only two blocks from a downtown typically crowded with diners, drinkers and eventgoers on a Saturday night.

“It’s a miracle no other bystanders were seriously injured or wounded in this,” Gallagher said.

Some members of Schmoyer’s family who spoke to The Morning Call in the days after the explosion said he was kind, fun-loving and would never do anything to hurt his son.

In a Facebook message sent after the news conference, Schmoyer’s younger sister, Tina Schmoyer, wrote: “A wonderful Father, Brother, Son, Boyfriend, Cousin, Nephew, Grandson, Great Grandson, and soon would be Uncle as well. Someone who’s heart was always for others and would give the shirt off his back to anyone in need.”

Schmoyer’s grandmother, Kathleen Pond of Washington Township, Lehigh County, received one of the letters Tuesday. On her Facebook page, she recounted the tumult of the past few days.

“Sunday morning my life changed for the worst, Tuesday evening upon returning home it changed once again,” she wrote. “Now, the news conference, will change it once more. It is like riding a roller coaster and we will stay on together until that ride is over ... Jacob I am still here with you!”

The deaths of Schmoyer’s son and Hallman were Allentown’s ninth and 10th homicides of 2018.

Some of Schmoyer’s family members said they did not think he knew anything about explosives. But in a 2010 Facebook post, Schmoyer referenced thermite, a compound often found in online bomb instructions.

“omg got a pound of thermite and enough magnesium to roast an entire cow,” reads the post from Sept. 2, 2010.

Robinson would not elaborate on why Schmoyer decided to kill his son or why he targeted Hallman. He said Schmoyer “lured” Hallman to the car.

Parents who kill their children are rare, according to academic research. A 2005 study published in the Journal of the American Academy of Psychiatry and the Law said that 40 to 60 percent of fathers who kill their offspring also commit suicide. The study examined 30 documented cases of what is known as “filicide-suicide,” and none involved the use of explosives, with three-quarters relying upon guns.

Authorities said at a news conference Thursday that Jacob Schmoyer sent four letters admitting his role in an Allentown murder-suicide explosion that took the life of his toddler son and an acquaintance.

“There are letters stating he had something against autism, which he suspected JJ had,” Rehrig said. “He murdered an innocent child. That is evil.”

Kerecz wanted to believe Schmoyer wasn’t capable of harming his son but reading the letter changed her mind.

“She always announced herself as Jake’s wife and today she said she is not his wife,” Rehrig said.

She added that her family can’t understand why Schmoyer didn’t reach out for help “if he had a problem and something was going on mentally and he had a breakdown.”

On Thursday, Rehrig and her family were not only processing news of what happened, but also planning JJ’s funeral.

Riley Yates / The Morning Call

A memorial at the North Lumber Street, Allentown, home where 2-year-old Jonathan Schmoyer lived with his father, Jacob G. Schmoyer, and mother.

A memorial at the North Lumber Street, Allentown, home where 2-year-old Jonathan Schmoyer lived with his father, Jacob G. Schmoyer, and mother. (Riley Yates / The Morning Call)

Christine Erdman, Hallman’s niece, said she is bewildered by the idea that Schmoyer targeted him. While some of Schmoyer’s relatives insisted the men didn’t know each other, Erdman said they were friends.

“I didn’t know Jacob but as far as I know they worked together, [Hallman] has been there for him, given him things,” she said. “And obviously that’s what he was meeting him for, thinking he was going to help him again.”

Surveillance video viewed by The Morning Call on Wednesday showed Hallman, who lived just doors from the scene, getting into Schmoyer’s car. About two seconds after he shuts the door, the Nissan explodes into a fireball.

The investigation showed the device, composed of two explosives Robinson would not identify, was either in the center console of the vehicle or near the passenger seat. Schmoyer was in the driver’s seat, Hallman in the front passenger seat and JJ strapped in a baby carrier in the rear seat, according to the ATF reconstruction.

Asked about Schmoyer’s familiarity with bombs, Robinson said how-to information on making the devices is widely available.

PHOTO GALLERY: A car explosion in Allentown on Turner Street killed three people Saturday night, Sept. 29, 2018. Scenes from the blast aftermath and the ongoing investigation.

“There's a lot of freedom of information. A lot of information out there. Now with the click of a mouse, you can get it,” he said.

The story has drawn national attention and Allentown City Hall was jammed with media as authorities revealed their conclusions Thursday morning.

PHOTO GALLERY: State and Federal agencies gathered at the Allentown City Hall council chamber to inform the public during a press conference Thursday, October 4, 2018 in Allentown on their findings on the car explosion on Turner Street last Saturday that killed three people. “It is the collective assessment and opinion of the entire investigative team that this was an intentional act … by Jacob Schmoyer,” Special Agent Don Robinson of the Bureau of Alcohol, Tobacco and Firearms said at a news conference.